Process for removing a contaminant from coal tar

ABSTRACT

A process for removing at least one contaminant from coal tar is described. The process involves extraction with an extraction agent or adsorption with an adsorbent. The extraction agent includes at least one of amphiphilic block copolymers, inclusion complexes of poly(methyl methacrylate) and polycyclic aromatic hydrocarbons, cyclodextrins, functionalized cyclodextrins, and cyclodextrin-functionalized polymers, and the adsorbent includes exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds.

This application claims the benefit of Provisional Application Ser. No.61/905,895 filed Nov. 19, 2013, entitled Process for Removing aContaminant from Coal Tar.

BACKGROUND OF THE INVENTION

Many different types of chemicals are produced from the processing ofpetroleum. However, petroleum is becoming more expensive because ofincreased demand in recent decades.

Therefore, attempts have been made to provide alternative sources forthe starting materials for manufacturing chemicals. Attention is nowbeing focused on producing liquid hydrocarbons from solid carbonaceousmaterials, such as coal, which is available in large quantities incountries such as the United States and China.

Pyrolysis of coal produces coke and coal tar. The coke-making or“coking” process consists of heating the material in closed vessels inthe absence of oxygen to very high temperatures. Coke is a porous buthard residue that is mostly carbon and inorganic ash, which is used inmaking steel.

Coal tar is the volatile material that is driven off during heating, andit comprises a mixture of a number of hydrocarbon compounds. It can beseparated to yield a variety of organic compounds, such as benzene,toluene, xylene, naphthalene, anthracene, and phenanthrene. Theseorganic compounds can be used to make numerous products, for example,dyes, drugs, explosives, flavorings, perfumes, preservatives, syntheticresins, and paints and stains but may also be processed into fuels andpetrochemical intermediates. The residual pitch left from the separationis used for paving, roofing, waterproofing, and insulation.

Coal tar has a number of contaminants that need to be removed, such asnitrogen, oxygen, or sulfur-containing compounds.

There is a need for additional processes for removing contaminants fromcoal tar.

SUMMARY OF THE INVENTION

One aspect of the invention is a process for removing at least oneproduct from coal tar. In one embodiment, the process includes providingat least a portion of a coal tar stream; removing at least onecontaminant from the at least the portion of the coal tar stream byextraction with an extraction agent or adsorption with an adsorbent toform a treated coal tar stream having a reduced level of the at leastone contaminant, the extraction agent comprising at least one ofamphiphilic block copolymers, inclusion complexes of poly(methylmethacrylate) and polycyclic aromatic hydrocarbons, cyclodextrins,functionalized cyclodextrins, and cyclodextrin-functionalized polymers,the adsorbent comprising exfoliated graphite oxide, thermally exfoliatedgraphite oxide or intercalated graphite compounds, and the at least onecontaminant comprising nitrogen heterocyclic aromatics, oxygenheterocyclic aromatics, and sulfur heterocyclic aromatics; andseparating the at least the portion of the coal tar stream into at leasttwo fractions.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is an illustration of one embodiment of the process of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The FIGURE shows one embodiment of a coal conversion process 5. The coalfeed 10 can be sent to the pyrolysis zone 15, the gasification zone 20,or the coal feed 10 can be split into two parts and sent to both.

In the pyrolysis zone 15, the coal is heated at high temperature, e.g.,up to about 2,000° C. (3600° F.), in the absence of oxygen to drive offthe volatile components. Coking produces a coke stream 25 and a coal tarstream 30. The coke stream 25 can be used in other processes, such asthe manufacture of steel.

The coal tar stream 30 which comprises the volatile components from thecoking process can be sent to an optional contaminant removal zone 35,if desired.

The contaminant removal zone 35 for removing one or more contaminantsfrom the coal tar stream or another process stream may be located atvarious positions along the process depending on the impact of theparticular contaminant on the product or process and the reason for thecontaminant's removal, as described further below. For example, thecontaminant removal zone 35 can be positioned upstream of the separationzone 45, as shown in the FIGURE. Some contaminants have been identifiedto interfere with a downstream processing step or hydrocarbon conversionprocess, in which case the contaminant removal zone 35 may be positionedupstream of the separation zone 45 or between the separation zone 45 andthe particular downstream processing step at issue. Still othercontaminants have been identified that should be removed to meetparticular product specifications. Where it is desired to removemultiple contaminants from the hydrocarbon or process stream, variouscontaminant removal zones may be positioned at different locations alongthe process. In still other approaches, a contaminant removal zone mayoverlap or be integrated with another process within the system, inwhich case the contaminant may be removed during another portion of theprocess, including, but not limited to the separation zone or thedownstream hydrocarbon conversion zone. This may be accomplished with orwithout modification to these particular zones, reactors, or processes.While the contaminant removal zone is often positioned downstream of thehydrocarbon conversion reactor, it should be understood that thecontaminant removal zone in accordance herewith may be positionedupstream of the separation zone, between the separation zone and thehydrocarbon conversion zone, or downstream of the hydrocarbon conversionzone or along other streams within the process stream, such as, forexample, a carrier fluid stream, a fuel stream, an oxygen source stream,or any streams used in the systems and the processes described herein.The contaminant concentration is controlled by removing at least aportion of the contaminant from the coal tar stream 30. As used herein,the term removing may refer to actual removal, for example byadsorption, absorption, or membrane separation, or it may refer toconversion of the contaminant to a more tolerable compound, or both.

Conventional contaminant removal methods can be used for the optionalcontaminant removal zone 35, including, but not limited to, adsorptionand oxidation. Typical adsorbents include, but are not limited to, anoble metal deposited on a support selected from the group consisting ofmolecular sieves, alumina, activated carbons, and silica gel; silverimpregnated zeolite selected from the group consisting of faujasites(13X, CaX, NaY, CaY, and ZnX), chabazites, clinoptilolites and LTA (3A,4A, 5A) zeolites; sulfur or a metal sulfide on an activated carbonsupport or an activated alumina support; or a metal sulfide, metaloxide, or metal carbonate on a support, the metal is selected from thegroup consisting of copper, silver, gold, antimony, lead, and manganese,and the support selected from the group consisting of activated alumina,clay, or activated carbon.

The viscosity of the coal tar stream can be reduced before it iscontacted with the extraction agent or adsorbent using any suitablemethod, if desired. The viscosity can be reduced before or after theoptional contaminant removal zone, for example. Suitable methods forreducing the viscosity of the coal tar stream include, but are notlimited to, mixing the coal tar stream with a solvent (not shown).

The decontaminated coal tar stream 40 from the contaminant removal zone35 is sent to a separation zone 45 where it is separated into two ormore fractions. Coal tar comprises a complex mixture of heterocyclicaromatic compounds and their derivatives with a wide range of boilingpoints. The number of fractions and the components in the variousfractions can be varied as is well known in the art. A typicalseparation process involves separating the coal tar into four to sixstreams. For example, there can be a fraction comprising NH₃, CO, andlight hydrocarbons, a light oil fraction with boiling points between 0°C. and 180° C., a middle oil fraction with boiling points between 180°C. to 230° C., a heavy oil fraction with boiling points between 230 to270° C., an anthracene oil fraction with boiling points between 270° C.to 350° C., and pitch.

The light oil fraction contains compounds such as benzenes, toluenes,xylenes, naphtha, coumarone-indene, dicyclopentadiene, pyridine, andpicolines. The middle oil fraction contains compounds such as phenols,cresols and cresylic acids, xylenols, naphthalene, high boiling taracids, and high boiling tar bases. The heavy oil fraction containsbenzene absorbing oil and creosotes. The anthracene oil fractioncontains anthracene. Pitch is the residue of the coal tar distillationcontaining primarily aromatic hydrocarbons and heterocyclic compounds.

As illustrated, the coal tar feed 40 is separated into gas fraction 50containing gases such as NH₃ and CO as well as light hydrocarbons, suchas ethane, hydrocarbon fractions 55, 60, and 65 having different boilingpoint ranges, and pitch fraction 70.

Suitable separation processes include, but are not limited tofractionation, solvent extraction, and adsorption.

One or more of the fractions 50, 55, 60, 65, 70 can be furtherprocessed, as desired.

As illustrated, fraction 60 is sent to treatment zone 61 for extractionor adsorption.

In an extraction process, an extraction agent stream 62 is introducedinto the treatment zone 61 and contacts the decontaminated coal tarstream. The extraction agent stream 62 can be between 1 and 99 wt % ofthe mixture of extraction agent stream and coal tar stream in thetreatment zone. The extraction can be performed at a temperature between0° C. and 250° C. When the extraction agent contains a supercriticalcomponent, the temperature is that required for the supercriticalconditions of the chosen supercritical component.

The extraction agent and the product are separated. The extraction agentcan be recycled, if desired. At least one contaminant 63 is removed fromthe fraction 60. The contaminant(s) can then be recovered and sent foradditional treatment, if needed (not shown).

The extraction agent can be one or more of amphiphilic block copolymers,inclusion complexes of poly(methyl methacrylate) and polycyclic aromatichydrocarbons, cyclodextrins, functionalized cyclodextrins, andcyclodextrin-functionalized polymers.

Cyclodextrins (CDs) are cyclic oligosaccharides. They have acharacteristic toroidal shape that form well defined cavities. Thecavities are typically about 8 Å deep and have a diameter of about 5 to10 nm depending on the number of the glucose units. The outside of thecavity is hydrophilic because of the presence of hydroxyl groups, whilethe inner cavity is hydrophobic because of presence of carbon andhydrogen atoms. CDs can accommodate guest molecules in the cavity.Typically, the less polar part of the guest molecule is in the cavity,and the more polar part is outside. The hydroxyls on the outside of theCDs can be functionalized, and functionalized CDs can be polymerized.Ionic liquids can be used to functionalize CDs. CDs can befunctionalized to modify their properties and/or to introduce groupswith specific activity. Functionalization can involve one or morehydroxyl groups.

CDs, functionalized CDs, and CD-functionalized polymers are described inOndo et al., Interaction of Ionic Liquids Ions with NaturalCyclodextrins, J. Phys. Chem. B, 2011, 115, 10285-10297; He et al.,Interaction of Ionic Liquids Ions and β-Cyclodextrin, J. Phys. Chem. B,2009, 113, 231-238; Mahlambi et al., “Polymerization ofCyclodextrin-Ionic Liquid Complexes for the Removal of Organic andInorganic Contaminants from Water,” InTech 2011, 115-150,www.intechopen.com; Rogalski et al., Physico-Chemical Properties andPhase Behavior of the Ionic Liquid-β-Cyclodextrin Complexes, Int. J.Mol. Sci. 2013, 14, 16638-16655; Zheng et al., The Enhanced Dissolutionof β-Cyclodextrin in Some Hydrophilic Ionic Liquids, J. Phys. Chem. A,2010, 114, 3926-3931; Uemasu, Effect of Methanol-Water Mixture Solventon Concentration of Indole in Coal Tar Using α-Cyclodextrin asComplexing Agent, Sekiyu Gakkaishi, 34, (4), 371-374 (1991); each ofwhich is incorporated herein by reference.

Inclusion complexes of polymethyl methacrylate and polycyclic aromatichydrocarbons can also be used as extraction agents. Syndiotacticpolymethyl methacrylate can form a helical cavity in which polycyclicaromatic hydrocarbons are contained. Formation of inclusion complexes isdescribed in Kawauchi et al., Formation of the Inclusion Complex ofHelical Syndiotactic Poly(methyl methacrylate) and Polycyclic AromaticHydrocarbons, Macromolecules, 2011, 44, 3452-3457, which is incorporatedherein by reference.

Amphiphilic block copolymers have alternating hydrophilic polymer blocksand hydrophobic polymer blocks. The amphiphilic block copolymercomprises at least two blocks selected from polyethylene oxide (EO)blocks, polypropylene oxide (PO) blocks, butylene oxide (BO) blocks,silicone (SC) blocks, urethane (UO) blocks, polyurethane ionomer (PI)blocks, acrylate ionomer (AI) blocks, polymethylacryate (MA) blocks,polyacrylic acid (AA) blocks, and polyvinylidene chloride (VC) blocks.Examples of suitable amphiphilic block copolymers include, but are notlimited to, EO-PO, EO-PO-EO, PO-EO-PO, EO-BO, PI-EO, AI-EO, SI-EO, andthe like. There are typically two or three different blocks in the blockcopolymers.

Amphiphilic block copolymers are described in Tungittiplakorn et al.,“Engineered Polymeric Nanoparticles for Soil Remediation,” Environ. Sci.Technol. 2004, 38, 1605-1610; Tungittiplakorn et al., “EngineeredPolymeric Nanoparticles for Bioremediation of Hydrophobic Contaminants,”Environ. Sci. Technol. 2005, 39, 1354-1358; Qiao et al, “StabilizedMicelles of Amphoteric Polyurethane Formed by ThermoresponsiveMicellization in HCl Aqueous Solution,” Langmuir, 2008, 24, 3122-3126;Velasquez et al., Poly(vinylidene chloride)-Based Amphiphilic BlockCopolymers, Macromolecules, 2013, 46, 664-673; and U.S. Publication Nos.2013/0030131, 2008/0045687, each of which is incorporated herein byreference.

The CDs, functionalized CDs, CD-functionalized polymers, inclusioncomplexes of poly(methyl methacrylate) and polycyclic aromatichydrocarbons, and amphiphilic block copolymer can optionally bedissolved in ionic liquids, supercritical fluids, or both.Alternatively, they can be used without an ionic liquid, orsupercritical fluid, if desired.

Ionic liquids are non-aqueous, organic salts composed of ions where thepositive ion is charge balanced with a negative ion. These materialshave low melting points, often below 100° C., undetectable vaporpressure, and good chemical and thermal stability. The cationic chargeof the salt is localized over hetero atoms, such as nitrogen,phosphorous, sulfur, arsenic, boron, antimony, and aluminum, and theanions may be any inorganic, organic, or organometallic species.Suitable ionic liquids include, but are not limited to,imidazolium-based ionic liquids, pyrrolidinium-based ionic liquids,pyridinium-based ionic liquids, sulphonium-based ionic liquids,phosphonium-based ionic liquids, and ammonium-based ionic liquids, andcombinations thereof

Supercritical fluids are substances at a temperature and pressure abovethe critical point, where distinct liquid and gas phases do not exist.They have properties of both liquids and vapors. Suitable supercriticalfluids include, but are not limited to, supercritical carbon dioxide,supercritical ammonia, supercritical ethane, supercritical propane,supercritical butane, and supercritical water, and combinations thereof.In some embodiments, the gas fraction from the separation zone can beused as the source of the carbon dioxide or ammonia for thesupercritical carbon dioxide or supercritical ammonia.

Alternatively, the fraction 60 is sent to treatment zone 61 andcontacted with an adsorbent. The adsorption is typically performed attemperatures between about 0° C. and about 150° C. In one embodiment,after the adsorbent bed is fully loaded to capacity, a desorbent isintroduced into the bed, and the contaminant is then recovered from thedesorbent/contaminant mixture. Alternatively, the bed can be heated toremove the adsorbed contaminant. In some embodiments, the coal tarstream is piped to another adsorbent bed during desorption of the firstbed.

The adsorbent comprises exfoliated graphite oxide, thermally exfoliatedgraphite oxide or intercalated graphite compounds. Exfoliated graphiteoxide, thermally exfoliated graphite oxide, and intercalated graphitecompounds are described in Hristea et al., Characterization ofExfoliated Graphite for Heavy Oil Sorption, J. Thermal Anal. Andcalorimetry, Vol. 91 (2008) 3, 817-823; Tryba et al., Influence ofchemically prepared H₂SO₄-graphite intercalation compound (GIC)precursor on parameters of exfoliated graphite (EG) for oil sorptionfrom water, Carbon, 41 (2002) 2009-2025; Tryba et al., Exfoliatedgraphite as a New Sorbent for Removal of Engine Oils from Wastewater,Spill Science and Tech. Bull., Vol. 8, Nos. 5-6, 569-571; Toyoda et al.,Heavy oil sorption using exfoliated graphite New application ofexfoliated graphite to protect heavy oil pollution, Carbon, 38 (2000)199-210; and U.S. Pat. No. 7,658,901, each of which is incorporatedherein by reference.

The contaminants from the extraction or adsorption process include, butare not limited to, nitrogen heterocyclic aromatics, oxygen heterocyclicaromatics, and sulfur heterocyclic aromatics and combinations thereof.

In some embodiments, at least two contaminants are removed from thefraction 60. The first product can be removed using a first extractionagent or adsorbent, and then the second product can removed using asecond extraction agent or adsorbent.

As shown, the contaminants are removed from fraction 60. As will beunderstood by those of skill in the art, the treatment zone 61 can belocated in various positions along the process depending on the impactof the particular contaminant on the product or process, as discussedabove with respect to the optional contaminant removal zone 35. Thetreatment zone 61 could be located before, after, or in place of, theoptional contaminant removal zone 35, before or after the separationzone 45, or before or after the hydrocarbon conversion zone 75, as wellas in other suitable locations. When the treatment zone 61 is locatedafter the separation zone 45 as illustrated, a portion of the coal tarstream is treated (fraction 60 as illustrated). When the treatment zone61 is located before the separation zone 45, all or a portion of thecoal tar stream 30 could be treated.

The treated fraction 64 can be sent to one or more hydrocarbonconversion zones. For example, the treated fraction can be sent tohydrocarbon conversion zone 75 for hydrocracking, for example, toproduce product 85. Suitable hydrocarbon conversion zones include, butare not limited to, hydrotreating zones, hydrocracking zones fluidcatalytic cracking zones, alkylation zones, transalkylation zones,oxidation zones and hydrogenation zones.

Hydrotreating is a process in which hydrogen gas is contacted with ahydrocarbon stream in the presence of suitable catalysts which areprimarily active for the removal of heteroatoms, such as sulfur,nitrogen, oxygen, and metals from the hydrocarbon feedstock. Inhydrotreating, hydrocarbons with double and triple bonds may besaturated. Aromatics may also be saturated. Typical hydrotreatingreaction conditions include a temperature of about 290° C. (550° F.) toabout 455° C. (850° F.), a pressure of about 3.4 MPa (500 psig) to about27.6 MPa (4000 psig), a liquid hourly space velocity of about 0.5 hr⁻¹to about 4 hr⁻¹, and a hydrogen rate of about 168 to about 1,011 Nm³/m³oil (1,000-6,000 scf/bbl). Typical hydrotreating catalysts include atleast one Group VIII metal, preferably iron, cobalt and nickel, and atleast one Group VI metal, preferably molybdenum and tungsten, on a highsurface area support material, preferably alumina Other typicalhydrotreating catalysts include zeolitic catalysts, as well as noblemetal catalysts where the noble metal is selected from palladium andplatinum.

Hydrocracking is a process in which hydrocarbons crack in the presenceof hydrogen to lower molecular weight hydrocarbons. Typicalhydrocracking conditions may include a temperature of about 290° C.(550° F.) to about 468° C. (875° F.), a pressure of about 3.5 MPa (500psig) to about 20.7 MPa (3000 psig), a liquid hourly space velocity(LHSV) of about 1.0 to less than about 2.5 hr⁻¹, and a hydrogen rate ofabout 421 to about 2,527 Nm³/m³ oil (2,500-15,000 scf/bbl). Typicalhydrocracking catalysts include amorphous silica-alumina bases orlow-level zeolite bases combined with one or more Group VIII or GroupVIB metal hydrogenating components, or a crystalline zeolite crackingbase upon which is deposited a Group VIII metal hydrogenating component.Additional hydrogenating components may be selected from Group VIB forincorporation with the zeolite base.

Fluid catalytic cracking (FCC) is a catalytic hydrocarbon conversionprocess accomplished by contacting heavier hydrocarbons in a fluidizedreaction zone with a catalytic particulate material. The reaction incatalytic cracking is carried out in the absence of substantial addedhydrogen or the consumption of hydrogen. The process typically employs apowdered catalyst having the particles suspended in a rising flow offeed hydrocarbons to form a fluidized bed. In representative processes,cracking takes place in a riser, which is a vertical or upward slopedpipe. Typically, a pre-heated feed is sprayed into the base of the riservia feed nozzles where it contacts hot fluidized catalyst and isvaporized on contact with the catalyst, and the cracking occursconverting the high molecular weight oil into lighter componentsincluding liquefied petroleum gas (LPG), gasoline, and a distillate. Thecatalyst-feed mixture flows upward through the riser for a short period(a few seconds), and then the mixture is separated in cyclones. Thehydrocarbons are directed to a fractionator for separation into LPG,gasoline, diesel, kerosene, jet fuel, and other possible fractions.While going through the riser, the cracking catalyst is deactivatedbecause the process is accompanied by formation of coke which depositson the catalyst particles. Contaminated catalyst is separated from thecracked hydrocarbon vapors and is further treated with steam to removehydrocarbon remaining in the pores of the catalyst. The catalyst is thendirected into a regenerator where the coke is burned off the surface ofthe catalyst particles, thus restoring the catalyst's activity andproviding the necessary heat for the next reaction cycle. The process ofcracking is endothermic. The regenerated catalyst is then used in thenew cycle. Typical FCC conditions include a temperature of about 400° C.to about 800° C., a pressure of about 0 to about 688 kPa g (about 0 to100 psig), and contact times of about 0.1 seconds to about 1 hour. Theconditions are determined based on the hydrocarbon feedstock beingcracked, and the cracked products desired. Zeolite-based catalysts arecommonly used in FCC reactors, as are composite catalysts which containzeolites, silica-aluminas, alumina, and other binders.

Transalkylation is a chemical reaction resulting in transfer of an alkylgroup from one organic compound to another. Catalysts, particularlyzeolite catalysts, are often used to effect the reaction. If desired,the transalkylation catalyst may be metal stabilized using a noble metalor base metal, and may contain suitable binder or matrix material suchas inorganic oxides and other suitable materials. In a transalkylationprocess, a polyalkylaromatic hydrocarbon feed and an aromatichydrocarbon feed are provided to a transalkylation reaction zone. Thefeed is usually heated to reaction temperature and then passed through areaction zone, which may comprise one or more individual reactors.Passage of the combined feed through the reaction zone produces aneffluent stream comprising unconverted feed and product monoalkylatedhydrocarbons. This effluent is normally cooled and passed to a strippingcolumn in which substantially all C5 and lighter hydrocarbons present inthe effluent are concentrated into an overhead stream and removed fromthe process. An aromatics-rich stream is recovered as net stripperbottoms, which is referred to as the transalkylation effluent.

The transalkylation reaction can be effected in contact with a catalyticcomposite in any conventional or otherwise convenient manner and maycomprise a batch or continuous type of operation, with a continuousoperation being preferred. The transalkylation catalyst is usefullydisposed as a fixed bed in a reaction zone of a vertical tubularreactor, with the alkylaromatic feed stock charged through the bed in anupflow or downflow manner. The transalkylation zone normally operates atconditions including a temperature in the range of about 130° C. toabout 540° C. The transalkylation zone is typically operated atmoderately elevated pressures broadly ranging from about 100 kPa toabout 10 MPa absolute. The transalkylation reaction can be effected overa wide range of space velocities. That is, volume of charge per volumeof catalyst per hour, weight hourly space velocity (WHSV), is generallyin the range of from about 0.1 to about 30 hr⁻¹. The catalyst istypically selected to have relatively high stability at a high activitylevel.

Alkylation is typically used to combine light olefins, for examplemixtures of alkenes such as propylene and butylene, with isobutane toproduce a relatively high-octane branched-chain paraffinic hydrocarbonfuel, including isoheptane and isooctane. Similarly, an alkylationreaction can be performed using an aromatic compound such as benzene inplace of the isobutane. When using benzene, the product resulting fromthe alkylation reaction is an alkylbenzene (e.g. toluene, xylenes,ethylbenzene, etc.). For isobutane alkylation, typically, the reactantsare mixed in the presence of a strong acid catalyst, such as sulfuricacid or hydrofluoric acid. The alkylation reaction is carried out atmild temperatures, and is typically a two-phase reaction. Because thereaction is exothermic, cooling is needed. Depending on the catalystused, normal refinery cooling water provides sufficient cooling.Alternatively, a chilled cooling medium can be provided to cool thereaction. The catalyst protonates the alkenes to produce reactivecarbocations which alkylate the isobutane reactant, thus formingbranched chain paraffins from isobutane. Aromatic alkylation isgenerally now conducted with solid acid catalysts including zeolites oramorphous silica-aluminas.

The alkylation reaction zone is maintained at a pressure sufficient tomaintain the reactants in liquid phase. For a hydrofluoric acidcatalyst, a general range of operating pressures is from about 200 toabout 7100 kPa absolute. The temperature range covered by this set ofconditions is from about −20° C. to about 200° C. For at leastalkylation of aromatic compounds, the volumetric ratio of hydrofluoricacid to the total amount of hydrocarbons entering the reactor should bemaintained within the broad range of from about 0.2:1 to about 10:1,preferably from about 0.5:1 to about 2:1

In some processes, all or a portion of the coal feed 10 is mixed withoxygen 95 and steam 100 and reacted under heat and pressure in thegasification zone 20 to form syngas 105, which is a mixture of carbonmonoxide and hydrogen. The syngas 105 can be further processed using theFischer-Tropsch reaction to produce gasoline or using the water-gasshift reaction to produce more hydrogen.

Oxidation involves the oxidation of hydrocarbons to oxygen-containingcompounds, such as aldehydes. The hydrocarbons include alkanes, alkenes,typically with carbon numbers from 2 to 15, and alkyl aromatics, Linear,branched, and cyclic alkanes and alkenes can be used. Oxygenates thatare not fully oxidized to ketones or carboxylic acids can also besubjected to oxidation processes, as well as sulfur compounds thatcontain —S—H moieties, thiophene rings, and sulfone groups. The processis carried out by placing an oxidation catalyst in a reaction zone andcontacting the feed stream which contains the desired hydrocarbons withthe catalyst in the presence of oxygen. The type of reactor which can beused is any type well known in the art such as fixed-bed, moving-bed,multi-tube, CS IR, fluidized bed, etc. The feed stream can be flowedover the catalyst bed either up-flow or down-flow in the liquid, vapor,or mixed phase. In the case of a fluidized-bed, the feed stream can beflowed co-current or counter-current. In a CSTR the feed stream can becontinuously added or added batch-wise. The feed stream contains thedesired oxidizable species along with oxygen. Oxygen can be introducedeither as pure oxygen or as air, or as liquid phase oxidants includinghydrogen peroxide, organic peroxides, or peroxy-acids. The molar ratioof oxygen (O₂) to substrate to be oxidized can range from about 5:1 toabout 1:10. In addition to oxygen and alkane or alkene, the feed streamcan also contain a diluent gas selected form nitrogen, neon, argon,helium, carbon dioxide, steam or mixtures thereof As stated, the oxygencan be added as air which could also provide a diluent. The molar ratioof diluent gas to oxygen ranges from greater than zero to about 10:1.The catalyst and feed stream are reacted at oxidation conditions whichinclude a temperature of about 25° C. to about 600° C., a pressure ofabout 101 kPa to about 5,066 kPa and a space velocity of about 100 toabout 100,000 hr⁻¹.

Hydrogenation involves the addition of hydrogen to hydrogenatablehydrocarbon compounds. Alternatively hydrogen can be provided in ahydrogen-containing compound with ready available hydrogen, such astetralin, alcohols, hydrogenated naphthalenes, and others via a transferhydrogenation process with or without a catalyst. The hydrogenatablehydrocarbon compounds are introduced into a hydrogenation zone andcontacted with a hydrogen-rich gaseous phase and a hydrogenationcatalyst in order to hydrogenate at least a portion of thehydrogenatable hydrocarbon compounds. The catalytic hydrogenation zonemay contain a fixed, ebulated or fluidized catalyst bed. Alternativelythe hydrogenation process can be carried out in the liquid phase in aCSTR. This reaction zone is typically at a pressure from about 689 k Pagauge (100 psig) to about 13790 k Pa gauge (2000 psig) with a maximumcatalyst bed temperature in the range of about 177° C. (350° F.) toabout 454° C. (850° F.). The liquid hourly space velocity is typicallyin the range from about 0.2 hr⁻¹ to about 10 hr⁻¹ and hydrogencirculation rates from about 200 standard cubic feet per barrel (SCFB)(35.6 m³ /m³) to about 10,000 SCFB (1778 m³/m³).

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention. It being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims.

What is claimed is:
 1. A process for removing at least one contaminantfrom coal tar comprising: providing at least a portion of a coal tarstream; removing at least one contaminant from the at least the portionof the coal tar stream by extraction with an extraction agent oradsorption with an adsorbent to form a treated coal tar stream having areduced level of the at least one contaminant, the extraction agentcomprising at least one of amphiphilic block copolymers, inclusioncomplexes of poly(methyl methacrylate) and polycyclic aromatichydrocarbons, cyclodextrins, functionalized cyclodextrins, andcyclodextrin-functionalized polymers, the adsorbent comprisingexfoliated graphite oxide, thermally exfoliated graphite oxide orintercalated graphite compounds, and the at least one contaminantcomprising nitrogen heterocyclic aromatics, oxygen heterocyclicaromatics, and sulfur heterocyclic aromatics; separating the at leastthe portion of the coal tar stream into at least two fractions.
 2. Theprocess of claim 1 wherein the extraction agent comprises theamphiphilic block copolymer, and wherein the amphiphilic block copolymercomprises at least two blocks selected from polyethylene oxide blocks,polypropylene oxide blocks, butylene oxide blocks, silicone blocks,urethane blocks, polyurethane ionomer blocks, acrylate ionomer blocks,polymethylacryate blocks, polyacrylic acid blocks, and polyvinylidenechloride blocks.
 3. The process of claim 1 wherein the extraction agentfurther comprises an ionic liquid, or a supercritical fluid, or both. 4.The process of claim 3 wherein the extraction agent further comprisesthe ionic liquid, and wherein the ionic liquid is selected fromimidazolium-based ionic liquid, pyrrolidinium-based ionic liquid,pyridinium-based ionic liquid, sulphonium-based ionic liquids,phosphonium-based ionic liquids, and ammonium-based ionic liquids. 5.The process of claim 3 wherein the extraction agent further comprisesthe supercritical fluid, and wherein the supercritical fluid comprisessupercritical carbon dioxide, supercritical ammonia, supercriticalethane, supercritical propane, supercritical butane, or supercriticalwater.
 6. The process of claim 5 wherein the supercritical fluid is thesupercritical ammonia, wherein one of the separated fractions comprisesammonia, and wherein the ammonia in the fraction is processed into thesupercritical ammonia.
 7. The process of claim 5 wherein thesupercritical fluid is the supercritical carbon dioxide, wherein one ofthe separated fractions comprises carbon dioxide, and wherein the carbondioxide in the fraction is processed into the supercritical carbondioxide.
 8. The process of claim 1 wherein at least two contaminants areremoved, and wherein the first contaminant is removed using a firstextraction agent or adsorbent and wherein the second contaminant isremoved using a second extraction agent or adsorbent after the removalof the first contaminant and before separating the at least the portionof the coal tar stream into the at least two fractions.
 9. The processof claim 1 further comprising removing at least one additionalcontaminant by adsorption with a second adsorbent, or an oxidationreaction, the at least one additional contaminant comprising arsenic,metal compounds, mercury halides, elemental mercury, inorganic halides,organic halides, and coal tar insolubles, and wherein the secondadsorbent comprises a noble metal deposited on a support selected fromthe group consisting of molecular sieves, alumina, activated carbons,and silica gel; silver impregnated zeolite selected from the groupconsisting of faujasites (13X, CaX, NaY, CaY, and ZnX), chabazites,clinoptilolites and LTA (3A, 4A, 5A) zeolites; sulfur or a metal sulfideon an activated carbon support or an activated alumina support; or ametal sulfide, metal oxide, or metal carbonate on a support, the metalis selected from the group consisting of copper, silver, gold, antimony,lead, and manganese, and the support selected from the group consistingof activated alumina, clay, or activated carbon.
 10. The process ofclaim 1 further comprising reducing a viscosity of the at least theportion of the coal tar stream before removing the at least onecontaminant.
 11. The process of claim 10 wherein the viscosity isreduced by mixing the at least the portion of the coal tar fraction witha solvent.
 12. The process of claim 1 further comprising processing atleast one of the fractions to produce at least one product.
 13. Theprocess of claim 12 wherein the at least one fraction is processed by atleast one of hydrotreating, hydrocracking, fluid catalytic cracking,alkylation, transalkylation, oxidation, or hydrogenation.
 14. Theprocess of claim 1 wherein the at least one contaminant is removedbefore the at least the portion of the coal tar stream is separated intothe at least two fractions.
 15. The process of claim 1 wherein the atleast one contaminant is removed after the at least the portion of thecoal tar stream is separated into the at least two fractions.
 16. Aprocess for removing at least one contaminant from coal tar comprising:pyrolyzing a coal feed into a coal tar stream and a coke stream;removing at least one contaminant from at least a portion of the coaltar stream by extraction with an extraction agent or adsorption with anadsorbent to form a treated coal tar stream having a reduced level ofthe at least one contaminant, the extraction agent comprising at leastone of amphiphilic block copolymers, inclusion complexes of poly(methylmethacrylate) and polycyclic aromatic hydrocarbons, cyclodextrins,functionalized cyclodextrins, and cyclodextrin-functionalized polymers,the adsorbent comprising exfoliated graphite oxide, thermally exfoliatedgraphite oxide or intercalated graphite compounds, and the at least onecontaminant comprising nitrogen heterocyclic aromatics, oxygenheterocyclic aromatics, and sulfur heterocyclic aromatics: separatingthe coal tar portion into at least two fractions: and processing atleast one of the fractions to produce at least one product.
 17. Theprocess of claim 16 wherein the extraction agent comprises theamphiphilic block copolymer, and wherein the amphiphilic block copolymercomprises at least two blocks selected from polyethylene oxide blocks,polypropylene oxide blocks, butylene oxide blocks, silicone blocks,urethane blocks, polyurethane ionomer blocks, acrylate ionomer blocks,polymethylacryate blocks, polyacrylic acid blocks, and polyvinylidenechloride blocks.
 18. The process of claim 16 wherein the extractionagent further comprises an ionic liquid, or a supercritical fluid, orboth.
 19. The process of claim 16 further comprising reducing aviscosity of the coal tar fraction before removing the at least onecontaminant.
 20. The process of claim 16 wherein the at least onefraction is processed by at least one of hydrotreating, hydrocracking,fluid catalytic cracking, alkylation, transalkylation, oxidation, orhydrogenation.